How to compile a stop motion movie in the VSE with python?
The following script reads your control file (extended so that # is used to mark comments):

#Length_in_second/100|filename.ext|x|y in pixels
50|0001.png|0|0
100|0002.png|0|2


The script read the file names from the control files and add image strips to the VSE

import bpy
directory='X:\\New Folder\\'
filename= directory + 'control.txt'

# adapted from blender.stackexchange.com/questions/6101
old_type = area.type
area.type = 'SEQUENCE_EDITOR'

start = 0
for line in open(filename):
    line=line.rstrip("\n")
    # skip comments
    if line.find("#") == -1:
        time,image,x,y = line.split("|")
        # / 10 because 50 eq. 500ms; * 25 for 25 frames per sec 
        duration = float(time)/10*25
        end = start + duration
        bpy.ops.sequencer.image_strip_add(directory=directory, files=[{"name": image, "name": image }], frame_start=start, frame_end=end, channel=1)
        start = end

area.type = old_type




Something like this should work to get the values to update an edited file:

for s in bpy.data.scenes[0].sequence_editor.sequences:
    print("%d|%s|0|0" % (((s.frame_final_end- s.frame_final_start)/2.5), s.name ))


In order to print to a file see my answer here:How to export list of prop values as txt to a certain folder? And how to import them back?